/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.metrics;



import com.fasterxml.jackson.annotation.JsonFilter;

import com.google.auto.value.AutoValue;

import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.annotations.Experimental.Kind;



import javax.annotation.Nullable;

import java.util.function.BiFunction;

import java.util.function.Function;



/**

 * The results of a single current metric.

 *

 * <p>TODO(BEAM-6265): Decouple wire formats from internal formats, remove usage of MetricName.

 */

@Experimental(Kind.METRICS)

@JsonFilter("committedMetrics")

@AutoValue

public abstract class MetricResult<T> {

  /** Return the name of the metric. */

  public MetricName getName() {

    return getKey().metricName();

  };



  public abstract MetricKey getKey();



  /**

   * Return the value of this metric across all successfully completed parts of the pipeline.

   *

   * <p>Not all runners will support committed metrics. If they are not supported, the runner will

   * throw an {@link UnsupportedOperationException}.

   */

  public T getCommitted() {

    T committed = getCommittedOrNull();

    if (committed == null) {

      throw new UnsupportedOperationException(

          "This runner does not currently support committed"

              + " metrics results. Please use 'attempted' instead.");

    }

    return committed;

  }



  public boolean hasCommitted() {

    return getCommittedOrNull() != null;

  }



  /** Return the value of this metric across all attempts of executing all parts of the pipeline. */

  @Nullable

  public abstract T getCommittedOrNull();



  /** Return the value of this metric across all attempts of executing all parts of the pipeline. */

  public abstract T getAttempted();



  public <V> MetricResult<V> transform(Function<T, V> fn) {

    T committed = getCommittedOrNull();

    return create(

        getKey(), committed == null ? null : fn.apply(committed), fn.apply(getAttempted()));

  }



  public MetricResult<T> addAttempted(T update, BiFunction<T, T, T> combine) {

    return create(getKey(), getCommitted(), combine.apply(getAttempted(), update));

  }



  public MetricResult<T> addCommitted(T update, BiFunction<T, T, T> combine) {

    T committed = getCommittedOrNull();

    return create(

        getKey(), committed == null ? update : combine.apply(committed, update), getAttempted());

  }



  public static <T> MetricResult<T> attempted(MetricKey key, T attempted) {

    return new AutoValue_MetricResult<>(key, null, attempted);

  }



  public static <T> MetricResult<T> create(MetricKey key, Boolean isCommittedSupported, T value) {

    if (isCommittedSupported) {

      return create(key, value, value);

    }

    return attempted(key, value);

  }



  public static <T> MetricResult<T> create(MetricKey key, @Nullable T committed, T attempted) {

    return new AutoValue_MetricResult<T>(key, committed, attempted);

  }

}